In a shaft, the shear stress is not directly proportional to

Answer: Option C

Shear stress in a shaft is not directly proportional to the length of the shaft.

Key Points:

Shear stress in a shaft is primarily dependent on the torque applied, the radius of the shaft, and the modulus of rigidity.

The angle of twist is related to the length of the shaft, but the shear stress itself is independent of the length.

Shear stress varies linearly with the radius of the shaft and is directly proportional to the modulus of rigidity.

Therefore: The shear stress in a shaft is not directly proportional to the length of the shaft.